Ocean descent system method and means

ABSTRACT

IN OFFSHORE OIL PRODUCTION OPERATIONS, A PLATFORM IS INITIALLY SECURED TO THE OCEAN FLOOR, AND A SUBMERSIBLE HOUSING IS THEREAFTER HAULED DOWN FROM THE OCEAN SURFACE IN PRECISE DIRECTIONAL OREIENTATION WITH RESPECT TO THE PLATFORM, AS REQUIRED FOR MATING OF STRUCTURAL ATTACH CONNECTIONS THEREBETWEEN. ORIENTATION IS ACHIEVED BY USE OF A U-SHAPED HAWSEPIPE ON THE PLATFORM, THROUGH WHICH THE HAUL-DOWN HAWSER IS THREADED, THE PIPE ENDS BEING SPACED APART A FIXED DISTANCE. A GUIDE ARM SYSTEM MOUNTED ON THE HOUSING ENGAGES THE HAWSER AT TWO LOCATIONS SPACED APART A DISTANCE COINCIDING WITH THE MENTIONED PIPE ENDS. LOOKING CONNECTION ELEMENTS ON THE PLATFORM AND HOUSING INTERENGAGE AUTOMATICALLY DUE TO PRECISE ORIENTATION THEREBETWEEN AS THE HOUSING MOVES INTO MATING RELATIONSHIP WITH THE PLATFORM.

Oct. 5, 1971 R, 5, 300 3,609,981

OCEAN DESCENT SYSTEM METHOD AND MEANS Filed July 8, 1969 3 Sheets-Sheet1 INVENTOR. ROBERT G. COOK AM Q ATTORNEY Oct. 5, 1971 R. G. COOK3,609,981

OCEAN DESCENT SYSTEM METHOD AND MEANS III F/GTZ INVENTOR. ROBERT 6'.COOK A T TOR/V5 Y Oct. 5, 1971 R. G. cooK OCEAN DESCENT SYSTEM METHODAND MEANS 3 Sheets-Sheet Filed July 8. 1969 INVISNTOR. ROBERT 6. 600K gmax A T TORNE Y United States Patent Office 3,609,981 Patented Oct. 5,1971 3,609,981 OCEAN DESCENT SYSTEM METHOD AND MEANS Robert G. Cook, SanPedro, Califi, assignor to North American Rockwell Corporation FiledJuly 8, 1969, Ser. No. 839,993 Int. Cl. E021) 17/02 US. CI. 61-69 7Claims ABSTRACT OF THE DISCLOSURE In offshore oil production operations,a platform is initially secured to the ocean floor, and a submersiblehousing is thereafter hauled down from the ocean surface in precisedirectional orientation with respect to the platform, as required formating of structural attach connections therebetween. Orientation isachieved by use of a U-shaped hawsepipe on the platform, through whichthe haul-down hawser is threaded, the pipe ends being spaced apart afixed distance. A guide arm system mounted on the housing engages thehawser at two locations spaced apart a distance coinciding with thementioned pipe ends. Locking connection elements on the platform andhousing interengage automatically due to precise orientationtherebetween as the housing moves into mating relationship with theplatform.

BACKGROUND OF THE INVENTION Offshore oil production operations ascurrently practiced involve a multitude of economic and technologicallimitations which become rapidly more overwhelming as the depth of suchoperations increases. Recent interest in exploration and tapping ofsuboceanic oil fields in depths ten or twenty times greater than thosenow considered maximum will require development of new techniques andstructures never before achieved in the prior art. Thus, many of thecommon techniques used for oil drilling and production in water depthsof 300 to 600 feet are totally useless at depths beyond 600 feet.However, exploration plans currently envision oil drilling andproduction operations in depths of several thousand feet wherehydrostatic pressure completely prohibit diver support and otherexpedients now widely used.

SUMMARY OF THE INVENTION The invention in this case involves essentiallya twostep installation method for erecting complex structures on theocean floor at depths as much as 6,000 feet. The novel method beginswith installation of a polygonal base or platform 10 shown in FIG. 1secured to ocean floor 12 by a plurality of upright pilings orstanchions 14. Platform 10 has a deck or upper surface 16 containing acenter aperture 18 of essentially cylindrical form and concentric abouta center axis 20 longitudinal therethrough. Platform 10 is furtherprovided with a generally U-shaped hawsepipe 22 extending below thesurface of deck 16 and having opposite spaced-apart ends 24 and 26.Hawsepipe 22 is securely affixed to platform 10 by suitable means andforms a permanent part of the platform structure. Installation of hollowairtight housings, either in unitary capsule or segmented form asrequired to complete the installation of equipment or habitable quarterson platform 10, is illustratively shown by reference to hollow housingshown in FIG. 1. Housing 30 is further provided with a rigid projectingbrace or arm 34 having an elongate hollow cup or tubular fitting 36secured to the distal end thereof. Housing 30 is further provided withlocking means in the form of elongate probe 40 downwardly dependingtherefrom and centered within skirt portion 32 as shown in FIG. 1. Inthe descent mode, hawser 42 is secured at one end thereof to housing 30by suitable means such as pin and clevis assembly 44 and the hawser isthreaded through hawsepipe 22 and fitting 36 as suggested in FIG. 1,extending upwardly to a drum or motor driven winch (not shown) on theocean surface. Operation of the mentioned winch causes upward pull onhawser 42 along the portion thereof which penetrates fitting 36,resulting in downward pull of the hawser portion connected to housing30. Near the mating position between housing 30 and platform 10, it willbe understood that the rotational position and lateral location ofhousing 30 are both determined and controlled by the relationshipbetween hawsepipe 22 and arm 34. Thus, since the distance between clevisattachment 44 and fitting 36 substantially coincides with the distancebetween opposite ends 24 and 26 of hawsepipe 11, hawser 42 will pull orotherwise forcibly move fittings 36 and 44 into close proximity withends 24 and 26. The foregoing alignment function performed by thearrangement of hawser 42 within hawsepipe 22 results in preciseorientational congruity between probe 40 and center axis 20 of aperture18 so that the locking probe and receptacle mounted on housing 30 andplatform 10, respectively, will automatically interengage in a mannerparticularly shown by FIGS. 2, 4, and 5.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a side elevational view,partly in crosssection, of the novel structure with the two majorcomponents disengaged from each other,

FIG. 2 shows an isolated elevational view of a portion of the structureshown in FIG. 1 but with the two major structural components operativelyengaged,

FIG. 3 shows a side elevational view, partly broken away, of a portionof the structure shown in FIG. 1 but with the marker buoys and pilotlines operatively associated therewith,

FIG. 4 shows a cross-sectional isolated view of the locking probe in aninterim position of incomplate engagement between the two majorcomponent of FIG. 1, and

FIG. 5 shows a cross-sectional isolated view of the same structure as inFIG. 4 but with the probe in locking interengagement position securingtogether the two major components shown particularly in FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now in detail to thedrawings mentioned above and particularly to FIG. 1, it may be seen thatthe inventive concept in this case contemplates a base or platformstructure such as generally denoted by reference numerals 10. Basecomponent 10 is supported on the ocean floor 12 and in vertically spacedrelationship therewith by a plurality of upright pilings or stanchions14. Platform 10 may be substantially round or polygonal in plan view orany other convenient shape, but in any case should have sufficient sizeand strength to support and retain the apparatus, protective housings orother such items which are sought to be secured proximate the oceanfloor. For example, platform 10 may comprise a plurality of trusses in astar pattern projecting radially outwardly from a centerline 20.Platform 10 preferably has a substantially planar deck 16 containing acenter aperture 18 wherein suitable means are situated for lockingadditional structure to the platform in a manner described more fullybelow. Platform 10 also is formed with a hollow U- shaped hawsepipe 22permanently secured thereto and having opposite ends 24 and 26 spacedapart, upwardly directed, vertically oriented, and substantiallyparallel to each other. Hawsepipe 22 may be secured to platform 10 byany suitable means such as welded braces 28 shown in FIG. 1.

It will be understood that platform 10 and the elementssecured theretoas discussed above are initially mounted on the ocean floor beforeerection of the total structure contemplated in this case. After themounting of platform in the manner shown in FIG. 1, means are providedfor using hawsepipe 22 in subsequent operations for lowering deepoceanic structures into position on platform 10. Referring to FIG. 3,the foregoing means includes a pilotline 50 which is initially threadedthrough hawsepipe 22, preferably before platform 10 and componentsjoined thereto are installed on the ocean floor. Pilot line 50 shouldcomprise material having sufiicient strength and water resistance suchas nylon, and is long enough to reach the surface at each of its endswhile still threaded through hawsepipe. The opposite ends of line 50each have a buoyant mass or float 52 and 54 secured thereto, suitablelengths of line 50 being stowed in floats 52 and 54 both of which can bereleased by suitable means when line 50 is needed for use. Floats 52 and54 may be released from platform 10 by pulling lanyards 60a and 60b,which withdraw pins 56 and 58. Upon removal of pins 56 and 58, floats 52and 54 are enabled to rise to the surface dragging the end of line 50 towhich each float is attached. Thereafter, line 50 is used to install thehauldown cable or hawser 42 shown in FIG. 1, for example.Illustratively, float 54 may be removed from the end of line 50 on theocean surface, and one end of hawser 42 may be secured to line 50 inplace of the mentioned float. Thereafter, upward pulling are sought tobe secured proximate the ocan floor. For exforce on the end of line 50secured to float 52 on the surface by suitable means such as a winch(not shown), will result in downward pull of hawser 42 which shouldcontinue until the hawser is completely threaded through hawsepipe 22and returns to the ocean surface through end 24 of the pipe. Thereafter,the hauldown operation discussed below may begin.

With hawser 42 completely threaded through hawsepipe 22 as shown in FIG.1, for example, that portion of the hawser protruding from end opening26 is secured to buoyancy housing 30 by any suitable means such asclevis 44. Thus, a pair of downwardly depending brackets formed onhousing 30 has a looped end of hawser 42 secured releasably therebetweenby a removable pin 46 which may be conveniently connected to suchpin-pulling means as remotely operated cable 48 operatively associatedwith guide pulley 49 mounted on fitting 36.

Housing 30 incorporates stabilizing and control means co-operating withhawser 42 to maintain continuous direction orientation of the housingthroughout its descent from the ocean surface to the ocean floor. Thestated means include projecting arm support means 34 welded or otherwisesecured to a depending skirt portion 32 on housing 30. Arm 34 has ahollow cup or cable follower fitting 36 affixed on the distal endthereof and through which the end of hawser 42 protruding from endopening 24 of hawsepipe 22 penetrates. From the foregoing arrangement,it will be understood that upward force on the end of hawser 42 andopposite from its connection with housing 30 will cause downward pull onthe housing against the upward force resulting from buoyancy of thehousing as it is hauled down deeper toward the ocean floor. Duringdescent of housing 30 in the foregoing manner, rotation of the housingabout an axis through the same and corresponding generally with centeraxis in FIG. 1 is effectively prevented by interengagement of fit, ting36 and hawser 42. Moreover, since the spacing between the locations 36and 44 where hawser 42 engages housing and structural components securedthereto, is essentially equal to the lateral distance between ends 24and 26 of hawsepipe 22, it will be understood that housing 30 will belaterally and rotationally oriented in precise predeterminedrelationship with respect to platform 10 as required for interengagementof their respective attaching means, which function in the manner now tobe discussed.

The mentioned attachment or locking means includes an elongatesubstantially cylindrical probe 40 downwardly depending from housing 30as shown in FIG. 1, for example. Probe 40 is adapted to contact thesloping sides 62 of a generally conical receptacle 64 and to be guidedthereby into a position of substantially concentric alignment with axis20. Receptacle 64 is secured within center aperture 18 of platform 10,and is closely proximate probe 40 at the inner periphery of lower endportion 74 of the receptacle when both are fully operativelyinterengaged in locking position. Referring to FIG. 2, in the finalposition of interengagement between major components 10 and 30, probe 40is retained within receptacle 64 and relatively horizontal motion isrestrained by skirt lip 66 and platform earns 68 so that items 10 and 30are correctly and precisely oriented. Thus, the end 26 of hawsepipe 22is spaced from center axis 20 by a distance substantially coincidingwith the distance between the center longitudinal axis of probe 40 andthe center of clevis 44. The foregoing dimensional relationship,together with the fact the clevis 44 and fitting 36 are spaced apart alateral distance substantially coinciding with the distance between ends24 and 26, results in automatic alignment of probe 10 during the lastfew feet of downward travel of the housing.

Referring to FIGS. 4 and 5, it may be seen that probe 40 hassubstantially cylindrical portion 70 and a generally conical noseportion 72. Probe 40 extends from and is otherwise supported on hollowhousing 30 by suitable means including motor mount 80. Mount has amassive flange 82 joined to housing 30 for transferring loads betweenprobe 40 and the housing. Mount 80 further comprises an elongate,somewhat cylindrical portion 84 with a hydraulic or electric motor drivemeans 86 affixed on the upper end thereof and in sealing relationshiptherewith as suggested by ring seals 88 and 90 in FIG. 5. Mount 80 has apartition or flange-like projection 92 integrally formed therein andhaving a center aperture through which a jackscrew 94 extends from motor86 to the upper portion 70 of probe 40. Thus, jackscrew 94 operativelyengages the internal threads of a hole 96 formed in the center ofcylindrical portion 70 and concentric with the longitudinal axisthereof. Upper and lower flanges 98 and 100 on jackscrew 94 engage theopposite sides of partition 92 in the manner suggested by FIG. 5, thuspreventing relative vertical movement between the jackscrew and thepartition. From the foregoing structural arrangement, it will beunderstood that rotation of jackscrew 94 by operation of drive motor 86causes vertical translation of probe 40 relative to housing 30 due toforce transmitted between the threads of the jackscrew and those on theinside of hole 96. For reasons discussed below, probe 40 is in thelowermost position relative to motor mount 80 during the descent mode,and is moved upwardly by actuation of motor 86 only after docking ofhousing 30 on platform 10 is otherwise completed.

Guide and restraining means are also provided to prevent rotation ofprobe 40 during translational movement thereof caused by rotation ofjackscrew 94. The mentioned guide means may take the form of one or moredownwardly extending pins such as suggested by pins 102 and 104 weldedon or otherwise afiixed to partition 92 and extending into holes 106 and108 formed in probe 40 and in sliding relationship therewith assuggested in FIG. 5. Vertical sliding movement of cylindrical portion 70relative to the internal surface 110 of motor mount 80 is thus permittedby the operative relationship therebetween, while suitable sealing meansare provided to prevent or minimize sea water leakage and may take'formof 0 rings 112 and 114.

As further seen from FIG. 5, probe 40 includes selfactivatinginterlocking means in the form of pivoting projection plates or blades116 and 118 mounted within a hollow cavity in probe 40. Although onlytwo blades are shown in FIGS. 4 and 5, it will be understood that 'fouror more such blades may be used instead of only two. During the descentmode, blades 116 and 118 may remain extended in the position shown byFIGS. 1 and 5, for example, and are held in such position by suitableresilient means such as leaf springs or the like as shown by springs 120and 122 seen in FIGS. 4 and 5. Each of the stated springs bears againsta separate one of the blades 116 and 118 which are pivotally movableabout stationary pins 124 and 126, respectively. As probe 40 movesdownardly into receptacle 64, the narrow lower portion 74 of thereceptacle contacts the outer distal ends of blades 11-6 and 118 andearns both blades into the retracted position suggested by FIG. 4against the biasing force of springs 120 and 122. After probe 40 hasmoved downwardly through receptacle 64 a distance whereby blades 116 and118 no longer contact the inner peripheral surface of portion 74 on thereceptacle, both blades rotate outwardly through suitable slots in theopposite sides of cavity 130 under the force of springs 120 and 122about their respective pivot centers through pins 124 and 126.

With blades 116 and 118 thus extended, means are provided for preventingradial inward movement of both blades such as would be necessary toretract the same into cavity 130. The stated means may take the formshown in FIG. 4 showing downwardly depending flanges 128 secured orotherwise formed on the upper end of cavity 130. Centered betweenbrackets 128 a link 132 having a hole therein through which a pin 134extends in the manner shown by FIG. 4. Link 132 is joined to arelatively heavy mass 136 having a nose portion 138 and conical sidesurfaces 140. Pin 134 releasably retains link 132 between brackets 128in the position shown by FIG. 4 during descent of housing 30 and probe40 from the ocean surface. During the final stage of descent, after theprobe penetrates through receptacle 64 an amount sufficient to permitextension of blades 116 and 118 in the manner suggested by FIG. 5, pin134 is pulled by any suitable means such as a control line 142 eitherautomatically or manually operated upon complete interengagement ofprobe 40 and receptacle 64. When pin 46 is pulled laterally from theside of probe 40, mass 136, which has sufficient bulk or weight to dropvertically under the force of gravity, plunges downwardly into theposition shown by FIG. 5, whereby conical surface 140 forcibly camsblades 116 and 118 radially outwardly and the cylindrical portionretains the same in the extended position to resist any loads applied tothe blades which would tend to Withdraw the same. With blades 116 and118 thus firmly held in the extended position, motor 86 may be actuatedby any suitable remote means to rotate jackscrew 94 in a directionresulting in upward movement of probe 40, since the probe is in thedownwardly extended position in relation to motor mount 80 prior tointerlocking engagement with receptacle 64. Operation of motor 86 withblades 116 and 118 fully extended will result in upward movement ofprobe 40 until the bearing surfaces 144 and 146 of blades 116 and 118,respectively, contact the beveled edge 148 and 150 of lower portion 74of the receptacle. When the blades are in the position thus shown byFIG. 5, actuation of motor 86 may be terminated and housing 30 willremain firmly interlocked with platform by the structuralinterconnection thereof as suggested in FIG. 2, for example.

I claim:

1. In structure for securing apparatus on the ocean a first structuralcomponent adapted for support on said ocean floor,

a hollow generally U-shaped hawsepipe affixed to said first componentwith the opposite open ends of said tube each being substantiallyvertically oriented and upwardly directed,

a second structural component adapted for support on said firstcomponent and hawscr means including a hawscr attached at one endthereof to said second component threaded through said hawsepipe forhauling said second component down to said first component by pullingupwardly on the other end of said hawser opposite from said one end. 2.The structure set forth in claim 1 above, further including:

a projecting arm on said second component, and a tubular fitting affixedto the distal end of said projecting arm, said hawscr being slidablythreaded through said tubular fitting to maintain the directionalposition of said second structural component in general correspondencewith the relative position of said one hawser end and said other hawserend. 3. The structure set forth in claim 2 above, wherein: said one endof said hawscr is attached to said second structural component at apredetermined distance from said tubular fitting, said distancecorresponding to the distance between said opposite open ends of saidU-shaped hawsepipe. 4. The structure set forth in claim 1, furtherincluding: interengagable locking means on said first and secondstructural components for securing both said components together inrelatively fixed relationship, said locking means including an elongateprobe on said second structural component and receptacle means mountedon said first structural component and adapted to receive said probe. 5.The structure set forth in claim 4 above, further including:

extendable blade means in said probe for preventing removal of saidprobe from said receptacle during mutual interengagement thereof, andholding means in said probe for holding said blade means in extendedposition. 6. A method of assembling at least two structural componentson the ocean floor, comprising:

initially securing one of said components on the ocean floor, engaging amid-portion of a hawser with said one component and in slidingrelationship therewith, securing one end of said hawser to the other ofsaid structural components, and applying upward pulling force to the endof said hawscr opposite from said one end to cause downward pullingforce on said other structural component. 7. The method set forth inclaim 6 above, further including: p

providing directional guidance to said other structural component withrespect to said one component by engaging said other structuralcomponent with both upward and downward pulling portions of said hawscr.

References Cited UNITED STATES PATENTS 1,374,834 4/1921 Dooley 6l69 X3,421,579 1/1969 Manning 6l69 X 3,477,236 11/1969 Burrus 6146.53,504,740 4/1970 Manning 166.5

J. KARL BELL, Primary Examiner

